1. Field of the Invention
The present invention is related in general to panels forming a separation structure between a generally closed inner environment and an outer environment.
2. Discussion of the Related Art
In the present invention and in the appended claims the term xe2x80x9cpanelxe2x80x9d is intended to designate any planar or even curved substantially sheet-like element, employed as a separating element between an inner and an outer environment in the fields of buildings and road and railway vehicles. Accordingly the term xe2x80x9cpanelxe2x80x9d as used herein includes walls, partitions, diaphragms, architectural facades, plate glasses, windows, windscreens and the like which, secured to their supports, provide safety and protection from the outside, i.e. prevent intrusion of persons, objects, atmospheric agents, etc.
These panels however become in case of emergency an obstacle to the need of evacuation of people and things, for instance owing to a fire, a road or railway accident, gas leak, undesired door locking, insufficient escape ways in case of panic, etc. When the panel consists of a window of an armored car, generally comprising two or more sturdy glass sheets mutually joined together by a bonding agent, there is the serious problem that in case of accident or locking of the car doors and movable windows, the passengers may be trapped within the car without any chances of escape. As far as railway vehicles, for instance high-speed trains, are concerned, the window panels are held fixed and the access doors are located in critical areas, i.e. at the ends of the vehicle bodies which are most exposed to the consequences of crashes and thus to the risk of jamming. The trapping danger in case of accident is in this case evidently much higher.
In order to give a solution to the above problems, panel controlled self-elimination systems have been already proposed, providing panel collapsing by means of explosive micro-charges. The presently known proposals, with specific reference to windows for vehicles in general, substantially provide the following three solutions:
the explosive charge, positioned at the outside or at the inside of the window, operates striking members which in turn produce embrittlement of the window (U.S. Pat. No. 5,318,145; EP-A-13529; FR-A-2096188; FR-A-2051580);
the window, or a portion thereof, is circumscribed by an annular explosive string whose detonation produces window cutting or severing. This solution is particularly directed to transparent canopies of aircraft provided with pilot""s ejectable seat (U.S. Pat. No. 4,301,707; FR-A-2140605; FR-A-2125588; FR-A-2077846; U.S. Pat. No. 3,670,998);
pyrotechnic charges are applied to the support structure of the panel, for instance of an aircraft emergency door, so as to provide separation and outwardly ejection thereof (U.S. Pat. No. 4,407,468).
The above-listed solutions are all affected by the same critical drawback: detonation of the explosive charge produces a substantially uncontrolled panel deflagration with ejection of the panel as a whole, or of portions and fragments thereof, normally towards the outside of the environment delimited by the panel itself. Panel embrittlement with fragment ejection is absolutely dangerous and unacceptable, and owing to this reason the above-disclosed known solutions have not been significantly applied until today.
The object of the present invention is to overcome the above inconveniences, and to provide a collapsible panel and a method for the controlled elimination thereof in a safe way and substantially without any risks of ejection of parts of fragments thereof towards either the outer or the inner environment.
According to the invention this object is achieved essentially by virtue of a collapsible panel of the type set forth in the above, characterized in that it embodies within at least part of the mass thereof at least one explosive charge to which igniter and/or detonator means are operatively associated to operate detonation of the explosive charge so as to shiver the panel in a controlled way substantially within the plane thereof.
The explosive charge may be distributed over the panel plane, configured in a continuous band around the perimeter, or it may be concentrated in correspondence of a weak point thereof, particularly at a corner.
In either case breakage of the panel following piloted detonation of the explosive charge provides opening of an escape passage between the inner and outer environments in a prompt and efficient way, since the panel is reduced into very little incoherent fractions. In case the panel constitutes an element of a building structure, immediate generation of a passage even of a large size enables, for instance in case of supermarkets, banks and public offices, not only to prevent any obstacle to the crowd flow outwardly, but also to ensure quicker and easier interventions by the police and fire brigade whenever necessary, also unsheltering any aggressors which might employ, once having got in, those xe2x80x9cbarriersxe2x80x9d like barricades. Still in case the collapsible panel is constituted by a building structure element even of a large size, such as for instance a glass wall, the invention provides incorporating within the panel a retaining filiform structure designed to hold the fragments of the panel itself following detonation of the explosive charge. In practice this turns the collapsed panel into a kind of incoherent curtain which prevents piling up of glass splinters and rubbles on the ground and which can be easily passed through.
Further advantageous applications of the panel according to the invention may consist for instance of fire barriers in building blocks constituted by a large amount of premises even arranged on several floors, or in road galleries. In the event of fire, piloting even by means of a remote control and also from several locations collapsing of a wise composition of such fire barriers may enable quickly circumscribing the fire, thus safeguarding in a short time people within the interested area, and warrants their moving away and rescue.
Still another particularly advantageous application of the collapsible panel according to the invention consists of car windows (lateral windows, windscreen, rear window) of motor vehicle, and in particular of armored cars. As it is known an armored car window is generally constituted by two or more sturdy glass sheets mutually bonded together: in case of accident or door locking, these windows would seal the passengers within the car. To the contrary, collapsing of the windows according to the principles of the invention, following detonation of explosive charges possibly in synchronism with operation of passive inertial safety systems which the car may be equipped with, immediately provides exit passageways for the car occupants towards the outside, i.e. passageways for succourers towards the interior of the car. In this application the window has normally a stratified conformation with at least a pair of glass sheets joined together, typically by means of a transparent bonding agent. In this case the explosive charge is conveniently provided according to the invention as a thin and also transparent layer, interposed between these sheets and embodied within the bonding agent. Obviously, in case the windows is formed by more sheets mutually coupled together, the explosive layer may be embodied in correspondence of the bonding areas between each pair of adjacent sheets. Detonation of the explosive charge, started by the associated igniter and/or detonator, immediately propagates between the window sheet layers, causing embrittlement thereof.
In case of armored tempered windows, the shock wave for collapsing thereof may be produced by an explosive micro-charge concentrated in the weakest point of the panel, i.e. as already previously pointed out at a corner where two of its edges are merging. Splinter projection shall in this case be prevented by the usual polycarbonate or polyester film provided in correspondence of the glass surface facing towards the interior of the vehicle.
Explosives which can be employed in the collapsible panel according to the invention may simply consist of commonly employed gunpowder. In the case of windows and transparent panels in general a suitable explosive may be of the blasting gelatine, Dynamite Gomme A(copyright), or Octogen(copyright) type, which are preferred for the present invention. However, the explosive may also be of the xe2x80x9cwater-gelxe2x80x9d type which, besides being capable of activation in environments without air and even wet and underwater, is also transparent and resistant to temperature changes, namely has no instability problems due to insulation, green house effect and accidental shocks. Moreover this type of explosive is subjected neither to dulling over the time nor to detonation by sparks generated by projectile impact thereagainst.
The invention, defined in its essential elements in the appended claims, is directed besides the collapsible panel also to the method for controlled collapsing thereof.